mysql - 如何通过distinct实现group by

Question

我有一个包含两列的表: col1 |列2。我想选择其中 col2 为反对派空和 col1 并且只有一行重复行

我的 table :

// tablename [col1=integer | col2=varchar]
+-------+-------------+
| col1  |    col2     |
+-------+-------------+
|  1    |  anything1  |
|  2    |             |
|  3    |  anything3  |
|  3    |  anything3  |
|  4    |  anything4  |
|  5    |  anything5  |
|  5    |  anything5  |
|  6    |             |
|  7    |  anything7  |
+-------+-------------+

我想要这个输出:

// newtablename
+-------+-------------+
| col1  |    col2     |
+-------+-------------+
|  1    |  anything1  |
|  3    |  anything3  |
|  4    |  anything4  |
|  5    |  anything5  |
|  7    |  anything7  |
+-------+-------------+

我的查询:

select * from tablename where col2 <>'' group by col1

现在我想知道，如何通过 distinct 实现上述查询(而不是group by)？

Answer 1

你的意思是:

select distinct col1,col2 
from tablename 
where col2 <>'' 
order by col1